Code Definition

P2120 — Throttle / Pedal Position Sensor / Switch D Circuit

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Toyota

About P2120

P2120 is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P2120 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P2120 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

Drive by wire systems use redundant sensors so the engine control module always has a second opinion on how far the driver is pressing the accelerator. Sensor D is one element of that redundant set within the accelerator pedal position assembly, supplied with a regulated reference voltage and returning a signal that rises or falls proportionally with pedal travel. DTC P2120 sets when the module detects the sensor D circuit behaving abnormally, with the signal voltage outside its valid operating window, stuck at a fixed value, or moving erratically rather than tracking pedal movement smoothly. ...

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